The present invention is related to a marine propulsion system having an engine and a multi-speed transmission coupled to one another to provide mechanical power to, for example, one or more propellers that upon rotation propel a boat in a desired direction and, more particularly, to a propulsion system and method that uses an electronic controller for controlling operation of the engine and/or transmission without use of mechanical linkages.
As described in more detail in the context of FIG. 1, a known marine propulsion system has an automatic multi-speed transmission that is controlled by an electronic controller. Unfortunately, such known marine propulsion system suffers from various deficiencies. For example, such system has its electronic controller specifically designed for monitoring two engine parameters, and in particular uses engine revolution speed and engine load to generate a control signal in response to those two engine parameters. The control signal generated by the controller is, in turn, used to control shifting of the transmission. This known controller requires use of a signal supplied by engine sensors indicative of engine load. More specifically, the engine load is monitored by using an engine sensor either designed to sense engine manifold air pressure or to sense engine throttle valve position. Further, such controller appears to require use of cumbersome mechanical linkages between an operator control handle and the engine and/or transmission.
In view of the foregoing drawbacks, it is desirable to provide a marine propulsion system that advantageously eliminates cumbersome mechanical linkages, such as push-pull cables or rods, from the operator control handle to the engine and/or transmission for setting desired engine and/or transmission operational parameters by use of technology generally referred to as "fly-by-wire" technology, which up to now is believed to have been generally limited to aerospace or military applications. For example, any desired transmission setting, such as forward, neutral and reverse, that the operator selects can now be electromagnetically transmitted, in lieu of being mechanically transmitted via push-pull cables, from the operator control handle to a suitable electromechanical actuator in the transmission. It is further desirable for the propulsion system to have a controller that allows for generating respective shift commands for shifting the transmission from first to second gear or vice versa without having to depend on engine sensors indicative of an engine load signal.